The present invention relates to a disk drive device for performing recording and/or reproduction of information by irradiating optical beams onto a recording surface of a disk type recording medium such as a CD-R or CD-ROM.
It is generally known that such type of disk drive device can be operated at high rotational speed (for instance, double speed or fourfold speed) for improving a speed for reading out information that is recorded on a disk type recording medium (hereinafter referred to as xe2x80x9cdiskxe2x80x9d). However, owing to the drawback that vibration or noise is generated at higher rotational speeds in case mass eccentricity resides in the disk, various measures have been proposed to cope therewith.
For example, there are known various methods and devices for detecting an amount of mass eccentricity of tracks of a disk so as to enable an optical head pickup) to correctly detect tracks during seeking actions or the like and to enable rapid retrieving access (see, for example, Japanese Patent Application Laid-Open Publication No. 3-22228 (1991) or Japanese Patent Application Laid-Open Publication No. 60-147975 (1985)).
In case the rotational speed of the disk is high at the time of performing reproducing actions, it may be that high frequency signals that have been read out by the optical head are affected through surface swings or eccentricity of the disk owing to vibration such that tracking error signals are disturbed whereby posing actions (jumping actions in units of a single track for making the optical head remain on the same track of the disk) may result in failure. In view of this fact, it has been suggested for a device wherein a rotational speed of a disk at the time of posing action is made smaller than a rotational speed at the time of reproduction to thereby reduce influences of surface swings or mass eccentricity of the disk owing to vibration cause during posing actions (see, for instance, Japanese Patent Application Laid-Open No. 10-124979 (1998)).
In the above mentioned devices for detecting an amount of mass eccentricity of tracks of a disk as recited in the former publications, there are required additional signals of specified speed for detecting directions in order to obtain an amount of mass eccentricity. Further, since the tracking servo is not turned OFF during detection, it is difficult to detect swings in a lens free condition of the optical pickup so that noise and vibration that is uncomfortable for a user cannot be restrained through actions performed at high rotational speed. Also, the technique as recited in the latter publication is related to coping with situations that are performed during posing actions only. While it is also known for a technique of performing detection of vibration by means of an acceleration sensor that is provided in such a device, it will result in a more complicated structure and in higher costs.
The present invention has been made for solving the above problems, and it is an object thereof to provide a disk drive device with which noise or vibration that is uncomfortable for a user can be easily decreased by the arrangement of detecting vibration owing to mass eccentricity of a disk and suitably reducing the rotational speed at the time of performing reproducing actions.
In the present invention, a counting means counts a number of tracking errors in a condition in which a tracking servo is in an OFF condition, and in case the number of tracking errors has exceeded a specified threshold for detecting vibration, a control means reproduces information while turning the tracking servo and remaining servos ON at a rotational speed that is lower than a target rotational speed. The number of counted tracking errors may thus be made to correspond to the vibration owing to mass eccentricity of the disk so that swings in the lens of the optical head may also be detected, and in case the vibration is large, the rotational speed is decreased for performing reproducing actions. With this arrangement, generation of noise or vibration can be restrained.
The control means performs recording or reproduction of information by turning the tracking servo and remaining servos ON at a rotational speed that has been decreased in a step-wise manner in case the number of counts has exceeded the threshold to be a rotational speed that is in a range in which the number of counts does not exceed the threshold. With this arrangement, reproducing actions at a highest possible rotational speed can be performed while restraining generation of noise or vibration.
The control means performs automatic adjustments by performing low rotational driving while the tracking servo and remaining servos are in an ON condition before the counting means starts counting actions by turning the tracking servo OFF and immediately after the disk type recording medium has been loaded into the drive device. In such an automatic adjustment, adjustments of balances of tracking or focus errors may be performed so that detection of vibration can be thereafter performed in a suitably adjusted manner.